Influence of Screening and Drying on Low-Quality Wood Chips for Application in Small-Scale Gasification Plants

Before using low-quality wood chips for gasification on the small and medium scale (30-500 kW(el)), mechanical fuel pretreatment has to be employed to ensure the required fuel characteristics concerning particle size distribution and moisture. Two different low-quality wood assortments (calamity wood and roadside maintenance wood) were subjected to three different mechanical fuel pretreatment strategies and a detailed analysis was realized along the supply chains. The results reveal the enrichment in elements characteristic of soil contamination in the removed fine fraction. Gasification tests were successfully performed with the upgraded low-quality fuels in field trials and indicated comparable electrical efficiencies but higher supervision effort during plant operation.